1. Field of the Invention
The present invention relates to spin-coating apparatus for coating a substrate in the manufacturing a semiconductor device or the like. More particularly, the present invention relates to a baffle plate positioned under the substrate during the spin-coating process, and to structure by which the baffle plate and a clamping plate are detachably connected.
2. Description of the Related Art
In the manufacturing of semiconductor devices, photoresist is typically applied to a wafer using a spin-coating apparatus. A conventional spin-coating apparatus is illustrated in FIG. 1. The spin-coating apparatus includes a spin chuck 1, a baffle plate 2, an upper cup 3, and a lower cup 4.
A wafer W is loaded onto the spin chuck 1 and is firmly secured to an upper platen of the chuck 1 by a vacuum. Photoresist is dispensed onto a center of the wafer W and the wafer W is rotated by the spin chuck. Thus, centrifugal force spreads the photoresist uniformly over the entire surface of the wafer W.
The baffle plate 2, the upper cup 3 and the lower cup 4 surround the spin chuck 1 and are movable up and down relative to the spin chuck 1. In particular, the baffle plate 2, the upper cup 3 and the lower cup 4 are moved downwardly so that the spin chuck 1 is positioned at the top of the upper cup 3. In this state, a wafer W is loaded onto the spin chuck 1. Then, the baffle plate 2, the upper cup 3 and the lower cup 4 are moved upwardly to the position shown in the figure, whereupon the wafer W secured to the spin chuck 1 is spin coated. The baffle plate 2, the upper cup 3 and the lower cup 4 are lowered immediately after the spin-coating process is performed. Then the wafer W is unloaded from the spin chuck 1.
During operation, therefore, the baffle plate 2 is positioned under the spin chuck 1 to collect and discharge residue that is discharged outwardly off of the wafer W while the wafer W is being spin-coated. Thus, the baffle plate 2 should be cleaned at regular intervals. To this end, the baffle plate 2 is adapted to be easily detached from a clamping plate 5.
U.S. Pat. No. 6,179,915, Japanese Unexamined Patent Publication No. 2002-164277, and Korean Unexamined Patent Publication No. 2002-032058 disclose structure by which the baffle plate 2 and the clamping plate 5 are detachably engaged. In this structure, the baffle plate 2 is seated on the clamping plate 5 in such a way that the baffle plate 2 is not rotated. However, the baffle plate 2 is minutely vibrated up and down by the clamping plate 5 during the spin-coating process. Thus, the baffle plate 2 often collides against a bottom surface of the wafer W located above the baffle plate 2. As a result, the wafer breaks or is otherwise damaged.